MB-41658: Expand error message when non-dirty item found during persistence

PersistenceCallback::operator() should always find a dirty item _if_
the seqno matches however crash/warmup tests intermittently fail this
check.

Dump additional details to assist in diagnosing issue if it reoccurs.

Change-Id: Ifa581ef552a12c652cf9756a591e19cce3c18a73
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/137355
Tested-by: Build Bot <[email protected]>
Reviewed-by: Ben Huddleston <[email protected]>

Author: daverigby

engines/ep/src/persistence_callback.cc

@@ -21,6 +21,7 @@
 #include "item.h"
 #include "stats.h"
 #include "vbucket.h"
+#include <utilities/logtags.h>
 
 PersistenceCallback::PersistenceCallback() {
 }
@@ -45,7 +46,22 @@ void PersistenceCallback::operator()(TransactionContext& txCtx,
             auto res = vbucket.ht.findItem(*queuedItem);
             auto* v = res.storedValue;
             if (v && (v->getBySeqno() == queuedItem->getBySeqno())) {
-                Expects(v->isDirty());
+                if (!v->isDirty()) {
+                    // MB-41658: Found item _should_ always be dirty, but
+                    // crash/warmup tests intermittently fail this check. Dump
+                    // additional details to assist in diagnosing issue if it
+                    // reoccurs.
+                    std::stringstream itemSS;
+                    itemSS << *queuedItem;
+                    std::stringstream svSS;
+                    svSS << *v;
+                    throw std::logic_error(fmt::format(
+                            "PersistenceCallback::operator() - Expected "
+                            "resident item matching queuedItem to be dirty!\n"
+                            "\tqueuedItem:{}\n\tv:{}",
+                            cb::UserData{itemSS.str()},
+                            cb::UserData{svSS.str()}));
+                }
                 v->markClean();
             }
         }
@@ -127,4 +143,4 @@ void EPTransactionContext::setCallback(const queued_item& item,
 void EPTransactionContext::deleteCallback(const queued_item& item,
                                           KVStore::FlushStateDeletion state) {
     cb(*this, item, state);
-}
+}